Studies will be carried out to determine the inter-relationships between spinal cord flow, alterations of extracellular ions, membrane-bound enzymes, such as adenylate cyclase and Na-K ATPase, and neurophysiologic parameters following spinal cord injury. The aim of these studies is to develop a therapeutic regimen based on correction of some or all of these abnormalities. Specifically, agents that improve spinal cord blood flow either through stimulation of adenylate cyclase or through alterations in endogenous opiates (naloxone) will be rigorously tested. The hypothesis that spinal cord injury initiates pathologic free radical reactions that lead to progressive degeneration of the spinal cord will be tested by studying changes in antioxidants, cholesterol oxidation products, and prostaglandin pathways. Clinically, we will continue to randomize patients admitted to the Center in the methylprednisolone study being conducted by the Yale University Department of Epidemiology. We will continue to manage patients by early stabilization and decompression. Acute and follow-up studies of somatosensory evoked potentials will be done at 3, 6, and 12 month intervals. Other possible pharmacologic studies to be considered after completion of the steroid study include aminophylline and isoproterenol, as well as naloxone, depending on the outcome of laboratory trials currently being done.